摘要:

Direct epitaxial growth on silicon has advantages when fabricating monolithic integrated infrared focal‐plane arrays. We demonstrated that both (111)A and (111)B oriented CdTe layers can be grown on (100) Si substrates by molecular‐beam epitaxy. The surface morphology of the (111)A layer was rough, while that of the (111)B layer was smooth. The key determining polarity is the substrate temperature during preadsorption of Te2flux. We found a polarity transition at 450 to 500 °C, and (111)B layers grow above that temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113479

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

BaTiO3thin films were grown epitaxially on (100) MgO substrates by metalorganic chemical vapor deposition (MOCVD) at a temperature of 600 °C. This substrate temperature is the lowest reported temperature for the growth of epitaxial BaTiO3films by an MOCVD process. The films had a cube–cube orientation relationship with the substrate and were oriented with ana‐axis perpendicular to the substrate plane. Nanoscale energy dispersive x‐ray spectrometry measurements showed no evidence of interdiffusion between the film and substrate. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113480

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A novel diol based metalorganic route has been developed and employed to deposit BaTiO3films on Si and Pt coated Si substrates. Differential thermal analysis, thermogravimetric analysis, x‐ray photoelectron spectroscopy, and x‐ray diffraction collectively indicated that BaTiO3was formed through the reaction of Ba and Ti oxides at approximately 500 °C. The films were single phase, had no crystallographic texture, and contained no detectable impurities. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113481

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This letter reports the observation of the vacuum tunnel gap between two conductors using a high resolution transmission electron microscope. A 2.5 mm square micromachined tunneling microscope chip has been fabricated with a minimum feature size of 0.4 &mgr;m. The chip fits into a modified side‐entry type transmission electron microscope holder. The tunnel gap is controlled by a purpose‐built feedback controller. The micromachines work reliably during observation of the tip apex in a transmission electron microscope, allowing the voltage and current to be changed while the tunnel gap is observed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113482

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The bias‐enhanced nucleation (BEN) technique has been applied to TiC(111) substrates and resulted in deposition of oriented diamond particles. The orientation was observed via scanning electron microscopy. A dense region of oriented particles was not observed on the samples, presumably due to the excessive twinning of the diamond. However, micrographs taken throughout the substrate showed diamond particles having similar orientation with respect to each other. Some of the diamond particles showed evidence of azimuthal twist and tilting, resulting most likely from the ∼21% lattice mismatch. Raman spectra of the diamond crystals show a strong feature at 1332 cm−1, which is indicative of diamond, and smaller features at 1480 and 1602 cm−1due tosp2‐bonded carbon. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113483

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Cubic BN(c‐BN) films were deposited on cubic SiC (&bgr;‐SiC) films on Si(100) by ion‐assisted pulsed laser deposition. The films were nearly phase pure, withc‐BN fractions of up to ∼90% as determined by infrared spectroscopy. Cross‐sectional transmission electron microscopy showed that much of the film/substrate interface had a thin amorphous layer next to the &bgr;‐SiC, followed by hexagonal/turbostratic BN (h‐BN/t‐BN), and then polycrystallinec‐BN, as commonly observed on Si substrates. However, there are alsoc‐BN crystals that extend to within 10 A˚ of the SiC interface,withnointerveningh‐BN/t‐BNlayer. A sharp falloff inc‐BN content was observed for substrate temperatures <150 °C, and below 100 °Cc‐BN did not form for any ratio of the ion current flux to the deposition flux. At a different ion‐to‐substrate angle (20° closer to glancing incidence) the falloff inc‐BN content forT<150 °C was less sharp. The existence of a critical temperature forc‐BN formation does not result from a nitrogen deficiency at low temperature since film stoichiometry did not change with temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113484

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electron paramagnetic resonance (EPR) studies of low hydroxyl synthetic silica optical fibers have revealed the presence of a 13 G hyperfine splitting of the SiE’center which is associated with weakly bonded hydrogen molecules in the silica structure. The fibers were previously exposed to hydrogen at room temperature. During an annealing of the silica fibers at 100 °C in air, the 13 G doublet was observed to decline and disappear while the 74 G doublet and the SiE’signal were growing. The result correlates with the redistribution of hydrogen molecules and is relevant to the environmental aging that is encountered in fiber optical waveguides under certain conditions. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113485

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A method of surface treatment was found to enhance diamond chemical vapor deposition nucleation on nondiamond substrates such as Si, SiO2, and Al2O3. The nucleation density obtained by ultrasonic abrasion with diamond powder alone was found to be enhanced by a few orders of magnitude using a mixed slurry consisting of diamond and metal powders. No strong nucleation enhancement was observed using a metal slurry only for surface treatment. The metal powders used were W, Ta, Mo, Nb, Ti, Al, Fe, Ni, Cu, and Si. It is concluded that the enhanced nucleation is associated with a physico‐chemical modification of the substrate surface, attained through a cooperative effect of both the metal and diamond particles during the ultrasonic abrasion process. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113486

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The physical system under study is a quantum wire of roughly triangular cross section grown epitaxially in a V‐shaped groove on a patterned (100) surface of a cubic substrate. The walls of the groove are {111} planes of the substrate material, so that the wire extends along a ⟨110⟩ direction. For a given thickness, or depth, of the wire, an analysis is presented which leads to an estimate of the smallest elastic mismatch strain for which the wire remains stable against formation of misfit dislocations, in the spirit of the Matthews‐Bladeslee condition, taking into account both the free surface effect and the mismatch strain effect. Comparison is made with the experimental observations of T. Arakawa, S. Tsukamoto, Y. Nagamune, M. Nishioka, J.‐H. Lee, and Y. Arakawa [Jpn. J. Appl. Phys.32, L1377 (1993)]. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113487

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We describe growth by molecular‐beam epitaxy of InGaAlAs multilayers using a versatile and agile technique that allows a wide range of band gaps and strains for the individual layers. In our approach, the layers are most generally pseudoalloys produced by growing short‐period superlattices containing ternary or quaternary layers, in various combinations, without changing the temperatures of the single In, Ga, Al, and As effusion cells. To illustrate the method, we have designed, grown, and characterized a separate‐confinement, strained layer light‐emitting diode operating at 1.5 &mgr;m. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113442

出版商:AIP    

年代:1995

数据来源: AIP